Just wanted to pitch in, beat buddy now supports Midi commands, with new firmware update. Which definitely should sync with AX8, but I don't think the AX8 receives start/stop midi commands yet. Not sure if it's because the beat buddy isn't sending universal start/stop commands.
Another thing you could try is the midinome, that one sends standard MIDI commands like Start (0xFA) and Stop (0xFC) same thing as the beat buddy Midi clock, with metronome, but more of an in-ear metronome, less of a drum machine also, half as cheap.
I don't have my Ax8 anymore to test it with my midinome. But as soon as I get a chance I'll repost here.